Describe how the resting potential is maintained in a neurone, and what this resting potential value is.

The resting potential of a neurone is -70 mV, which means that it's more negative in the cytoplasm than in the tissue fluid. In the membrane there are sodium-potassium pumps which work using active transport and so need ATP. There are also sodium channel proteins and potassium channel proteins in the membrane which rely on facilitated diffusion. The sodium-potassium pump works by pumping 3 sodium ions out of the cell and 2 potassium ions into the cell which creates a concentration gradient. The sodium channels close more firmly than the potassium channels and so more potassium leaks out of the cell (diffusing down its concentration gradient) than sodium leaks into the cell, making the inside of the cell more negative and giving it a value of -70 mV.